Expected Effects of Global Warming on Thunderstorm Frequency and Severity

Meteorologists and climate scientists interested
in how global warming have conclusions about the impact warming will have on thunderstorm
frequency and severity.Thunderstorm frequency (related to the
slope of the environmental lapse rate) is not expected to change, but the
severity of thunderstorms is expected to increase.The latter is related to the expected
increase in the amount of water vapor in the boundary layer.

Since global warming is expected to affect all levels of the
troposphere equally, then the slope of the environmental lapse rate will be the
same.However, if this warming in
lower levels is matched by an increase in actual mixing ratios (more water
vapor and higher dew points), then the CAPE would be expected to increase
dramatically.For the case shown,
the LCL and LFC for all three scenarios are the same;a cloud base would be found at the
ground and the soundings are absolutely unstable.However, the CAPE for the warmest case
would be extremely large.

CAPE is a measure of the vertical acceleration due to
buoyancy.Since hail size and
downdraft wind strength are directly proportional to CAPE, average hail
diameters would increase and so would the strength of the downdraft winds.A greater percentage of hail stones
would meet the definition of severe hail, perhaps giant hail, and the number of
cases with straight line winds greater than 57 mph would increase

Fig.
1:Skew-T/log p diagram with an
initial sounding (far left) and then two soundings progressively associated
with increasing mean temperatures due to Global Warming.Note that the environmental lapse
rate,(ĘT/Ęz)e,
is identical in all three cases.Fig. 1 is duplicated in larger format at the end of the Homework.